Any idea what this cake tin is for?

I've been given a slightly odd cake tin. Circular, 8.5" across the base, 9.25" across the top. The strange thing is its height: 4.5" tall, nearly twice the height of an ordinary cake tin. It's non-stick, so can't be very old.

I have no idea what it's for (neither did its giver, which was why she gave it to me!).